Integrated device with vertical field-effect transistors and hybrid channels

ABSTRACT

An integrated semiconductor device includes a substrate, a first vertical transistor, and a second vertical transistor. The substrate has a first substrate region and a second substrate region. The first vertical transistor is disposed on the substrate in the first substrate region. The first vertical transistor is n-type field-effect vertical transistor (n-VFET) with a first channel crystalline orientation. The second vertical transistor is disposed on the substrate in the second substrate region. The second vertical transistor is p-type field-effect vertical transistor (p-VFET) with a second channel crystalline orientation. The first channel crystalline orientation is different from the second channel orientation. A common bottom source and drain region as well as common bottom and top spacers regions are provided for the first vertical transistor and the second vertical transistor.

DOMESTIC PRIORITY

This application is a divisional of U.S. patent application Ser. No.16/192,896, filed Nov. 16, 2018, the disclosure of which is incorporatedby reference herein in its entirety.

BACKGROUND

The present invention generally relates to fabrication methods andresulting structures for semiconductor devices. More specifically, thepresent invention relates to an integrated semiconductor device withvertical field-effect transistors and hybrid channels.

Semiconductor structures or devices can be embodied as vertical fieldeffect transistors (VFETs). Performance and behavior characteristics ofVFETs are influenced by the material of the device active regions. Forexample, p-type and n-type VFETs (p-VFET and n-VFET, respectively) haveperformance characteristics that depend on a material of the channels.Choosing the appropriate channel material for the different transistortypes (e.g. p-VFET and n-VFET) is important in optimizing devices'performance. For example, p-VFETs are known to have better hole mobilityusing a silicon channel with a (111) or (110) crystal surfaceorientation (Si (111) or Si (110), respectively) than a silicon channelwith a (100) crystal surface orientation (Si (100)). On the other handn-VFET are known to have better electron mobility using a Si (100)channel than a Si(111) or Si(110) channel. Accordingly, it would beadvantageous to provide hybrid channel orientations, namely, Si (100)channel on n-VFET and Si (111) on p-VFET, in a single integratedsemiconductor circuit.

SUMMARY

According to a non-limiting embodiment of the present invention, anintegrated semiconductor device is provided that includes a substrate, afirst vertical transistor, and a second vertical transistor. Thesubstrate has a first substrate region and a second substrate region.The first vertical transistor is disposed on the substrate in the firstsubstrate region. The first vertical transistor is n-type field-effectvertical transistor (n-VFET) with a first channel crystallineorientation. The second vertical transistor is disposed on the substratein the second substrate region. The second vertical transistor is p-typefield-effect vertical transistor (p-VFET) with a second channelcrystalline orientation. The first channel crystalline orientation isdifferent from the second channel orientation. A common bottom sourceand drain region is provided for the first vertical transistor and thesecond vertical transistor. A common bottom spacer region for the firstvertical transistor and the second vertical transistor as well as acommon top spacer region for the first vertical transistor and thesecond vertical transistor are also provided.

Embodiments of the present invention are further directed to a methodfor fabricating an integrated semiconductor device. A non-limitingexample of the method includes providing a substrate including a firstsubstrate region and a second substrate region. The method furtherincludes forming a first vertical transistor on the substrate in thefirst substrate region. The first vertical transistor is n-typefield-effect vertical transistor (n-VFET) with a first channelcrystalline orientation. Even further, the method includes forming asecond vertical transistor on the substrate in the second substrateregion. The second vertical transistor is p-type field-effect verticaltransistor (p-VFET) with a second channel crystalline orientation. Thefirst channel crystalline orientation is being different from the secondchannel orientation. In addition, the method provides for forming acommon bottom source and drain region for the first vertical transistorand the second vertical transistor. Even further, the method providesfor forming a common bottom spacer region for the first verticaltransistor and the second vertical transistor as well as forming acommon top spacer region for the first vertical transistor and thesecond vertical transistor.

According to yet another non-limiting embodiment, a method offabricating an integrated semiconductor device includes forming a firstfin channel and a second fin channel on a substrate with a firstsubstrate region and a second substrate region. The first fin channel isformed in the first substrate region and the second fin channel isformed in the second substrate. The first fin channel includes silicon(Si) with (100) crystal orientation (Si (100)) and the second finchannel includes silicon (Si) with (111) crystal orientation (Si (111)).The method further includes modifying the first fin channel into an-type vertical field-effect transistor (n-VFET) and modifying thesecond fin channel into a p-type vertical field-effect transistor(p-VFET). In addition, the method provides for forming a common bottomsource and drain region for the n-VFET and the p-VFET. Even further, themethod provides for forming a common bottom spacer region for the n-VFETand the p-VFET as well as forming a common top spacer region for then-VFET and the p-VFET.

Additional technical features and benefits are realized through thetechniques of the present invention. Embodiments and aspects of theinvention are described in detail herein and are considered a part ofthe claimed subject matter. For a better understanding, refer to thedetailed description and to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The specifics of the exclusive rights described herein are particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features and advantages ofthe embodiments of the invention are apparent from the followingdetailed description taken in conjunction with the accompanying drawingsin which:

FIG. 1 depicts a cross-sectional view illustrating a starting structurefor fabricating an integrated semiconductor device in accordance withembodiments of this invention;

FIG. 2 depicts a cross-sectional view illustrating fin structures beinggrown, patterned and etched on a substrate in accordance withembodiments of this invention;

FIG. 3 depicts a cross-sectional view illustrating formation of a p-typetransistor in a second substrate region in accordance with embodimentsof this invention;

FIG. 4 depicts a cross-sectional view illustrating formation ofsemiconductor layers in the second substrate region in accordance withembodiments of this invention;

FIG. 5 depicts a cross-sectional view illustrating formation of a hardmask over upper surfaces of the semiconductor layers in accordance withembodiments of this invention;

FIG. 6 depicts a cross-sectional view illustrating formation of a firstchannel and a second channel in accordance with embodiments of thisinvention;

FIGS. 7 and 8 illustrate formation of top spacers over the first andsecond channels and deposition of interlayer dielectric (ILD) materialin accordance with embodiments of this invention;

FIG. 9 depicts a cross-sectional view illustrating formation of a bottomsource drain layer in accordance with embodiments of this invention;

FIG. 10 depicts a cross-sectional view illustrating formation of bottomspacers in accordance with embodiments of this invention;

FIG. 11 depict a cross-sectional view illustrating formation of bottomspacers in accordance with embodiments of this invention;

FIG. 12 depicts a cross-sectional view illustrating formation of a gatedielectric layer and deposition of ILD material in accordance withembodiments of this invention;

FIG. 13 depicts a cross-sectional view illustrating formation of a gatelayer and recession of ILD material in accordance with embodiments ofthis invention;

FIG. 14 depicts a cross-sectional view illustrating deposition of a topspacer metal in accordance with embodiments of this invention; and

FIG. 15 depicts a cross-sectional view illustrating the integratedsemiconductor device with vertical field-effect transistors inaccordance with embodiments of this invention.

In the accompanying figures and following detailed description of thedescribed embodiments, the various elements illustrated in the figuresare provided with two or three digit reference numbers. With minorexceptions, the leftmost digit(s) of each reference number correspond tothe figure in which its element is first illustrated.

DETAILED DESCRIPTION

For the sake of brevity, conventional techniques related tosemiconductor device and integrated circuit (IC) fabrication may or maynot be described in detail herein. Moreover, the various tasks andprocess steps described herein can be incorporated into a morecomprehensive procedure or process having additional steps orfunctionality not described in detail herein. In particular, varioussteps in the manufacture of semiconductor devices andsemiconductor-based ICs are well known and so, in the interest ofbrevity, many conventional steps will only be mentioned briefly hereinor will be omitted entirely without providing the well-known processdetails.

Turning now to an overview of technologies that are more specificallyrelevant to aspects of the invention, in present semiconductortechnology, for example, complementary metal oxide semiconductor (CMOS)technology, devices such as p-type and n-type VFETs (p-VFET and n-VFET,respectively) are typically fabricated upon semiconductor substrates,such as silicon (Si) substrates, which have a single crystalorientation. In particular, most of today's semiconductor devices arebuilt upon Si having a (100) crystal orientation (Si (100)).

Electrons are known to have a high mobility for a Si (100) surfaceorientation, but holes are known to have high mobility for a (111)surface orientation. In other words, hole mobility values on Si (100)are roughly 2×-4× lower than the corresponding electron mobility for(111) crystallographic orientation. To compensate for this discrepancy,p-VFETs are typically designed with larger widths in order to balancepull-up currents against the n-VFET pull-down currents and achieveuniform circuit switching. P-VFETs having larger widths are undesirablebecause they take up a significant amount of chip area. On the otherhand, hole mobilities on Si (111) are higher than on Si(100). Therefore,p-VFETs formed on a (111) surface will exhibit significantly higherdrive currents than n-VFETs formed on a (100) surface. Electronmobilities on Si (111) surfaces, however, are significantly degradedcompared to Si (100) surfaces. Accordingly, the Si (111) surface isoptimal for p-VFET devices because of excellent hole mobility, but sucha crystal orientation is not beneficial for n-VFET devices. Instead, theSi (100) surface is optimal for n-VFET devices because that crystalorientation favors electron mobility.

Conventional methods to form planar hybrid substrates with differentsurface orientations generally employ wafer bonding. More specifically,the planar hybrid substrate is obtained mainly throughsemiconductor-to-insulator, or insulator-to-insulator wafer bonding toachieve p-VFETS and n-VFETS on their own optimized crystal orientationfor high performance device manufacture. The disadvantage of such methodand configuration is that at least one type of MOSFET (either p-VFETS orn-VFETS) is on a semiconductor-on-insulator (SOI), while the other typeof MOSFET is either on a bulk semiconductor or an SOI with a thicker SOIfilm. Another conventional method for providing CMOS integrated circuits(ICs) with bulk-like p-VFETS and n-VFETS is achieved by shallow trenchisolation (STI). However, this method results in a device that consumesa large chip area requires deep STI depth. In view of the forgoing,there is a need for providing a structure having both p-VFETS andn-VFETS on a substrate with different crystal orientations.

Turning now to an overview of the aspects of the invention, one or moreembodiments of the invention address the above-described shortcomings ofthe prior art by providing an integrated device with vertical fieldeffect transistors and hybrid channels, namely, a (100) orientationn-VFET channel and a (111) orientation p-VFET channel fabricated byheteroepitaxial growth of a buffer layer (e.g. GaN layer) on siliconsubstrate with (100) orientation (Si (100)) with a bottom isolationlayer (e.g. Si_(x)N_(y) layer).

Turning now to a more detailed description of aspects of the presentinvention, FIG. 1 depicts a cross-sectional view of an integrated device100 after an initial set of fabrication operations according toembodiments of the invention. The integrated device 100 includes asemiconductor substrate 10, a semiconductor layer 12, and a hard masklayer 14, configured and arranged as shown. The semiconductor substrate10 can be a bulk substrate of a semiconductor material including, butnot limited to, silicon (Si), silicon germanium (SiGe), silicon carbide(SiC), silicon-germanium-carbon (SiGeC) or other like semiconductormaterial. Although silicon is the predominantly used semiconductormaterial in wafer fabrication, alternative semiconductor materials canbe employed, such as, but not limited to, germanium, gallium arsenide,gallium nitride, silicon germanium, cadmium telluride and zinc selenide.

In addition, multiple layers of the semiconductor materials can be usedas the semiconductor material of the semiconductor substrate 10, forexample, a semiconductor-on-insulator substrate (SeOI), asilicon-on-insulator substrate (SOI), a germanium-on-insulator substrate(GeOI) or a silicon-germanium-on-insulator substrate (SGOI). Thesemiconductor substrate 10 can also have other layers forming thesubstrate 10, including high-k oxides and/or nitrides. In embodiments ofthe invention, the semiconductor substrate 10 is a silicon with (100)orientation (Si (100)).

The starting structure shown in FIG. 1 further includes a semiconductorlayer 12, which can be, for example, silicon with (100) orientation. Thesemiconductor layer 12 is epitaxially grown over the semiconductorsubstrate 10. A hard mask 14 is formed over the upper surface of thesemiconductor layer 12. The hard mask 14 can be formed by anyconventional methods, such as, for example, chemical vapor deposition(CVD), plasma-enhanced chemical vapor deposition (PECVD), chemicalsolution deposition, atomic layer deposition, or physical vapordeposition. Alternatively, the hard mask 14 can be formed utilizing athermal oxidation, nitridation or oxynitridation process. The hard mask14 is composed of a dielectric material such as, for example, an oxide,nitride, oxynitride or a multilayered stack thereof. In embodiments ofthe invention, the hard mask 14 includes silicon mononitride (SiN).

In FIG. 2, the semiconductor layer 12 and the hard mask 14 are recessedin a second substrate region 112 by conventional patterning and etchingprocesses to form a fin shape at a first substrate region 111 in ann-VFET region 611 (shown in FIG. 6). The first substrate region 111 canbe used as a basis for the formation of a n-type transistor in then-VFET region 611 (shown in FIG. 6).

Further, as shown in FIG. 2, in embodiments of the invention, a masklayer 114 can be patterned using lithographical techniques. The masklayer 114 is used to protect the first substrate region 111 from, forexample, a reactive ion etch (RIE) or similar etching process that isemployed to create the recess in the second region 112.

In FIG. 3, a second semiconductor layer 216 is formed over thesemiconductor substrate 10 by epitaxial growth in the second substrateregion 112. FIG. 3 illustrates the initial stage of structuring a p-typetransistor in a p-VFET region 612 (shown in FIG. 6) by forming a finshape at the second substrate region 112. In an embodiment of theinvention, the second semiconductor layer 216 is composed of a III-Vmaterial.

The term III-V material, as used herein, refers to a material thatincludes at least one group III element and at least one group Velement. By way of example only, suitable III-V materials include, butare not limited to, aluminum antimonide, aluminum arsenide, aluminumgallium arsenide, aluminum gallium indium phosphide, aluminum galliumnitride, aluminum gallium phosphide, aluminum indium arsenide, aluminumnitride, aluminum phosphide, boron arsenide, boron nitride, boronphosphide, gallium antimonide, gallium arsenide, gallium arsenidephosphide, gallium indium arsenide antimonide phosphide, galliumnitride, gallium phosphide, indium antimonide, indium arsenide, indiumarsenide antimonide phosphide, indium gallium arsenide, indium galliumnitride, indium gallium phosphide, indium nitride, indium phosphideand/or combinations including at least one of the foregoing materials.

According to embodiments of the invention, the III-V material isepitaxially grown in the second substrate region 112 on thesemiconductor substrate 10 using a molecular-beam approach to form thesecond semiconductor layer 216. Molecular-beam epitaxy (MBE) is aprocess well known to those of skill in the art. In general, molecularbeam epitaxy is conducted under a vacuum (e.g., in a vacuum chamber)where component elements contained in separate effusion cells are heateduntil the elements sublimate. The resulting gaseous elements thencondense on the target substrate. In this case, the component elementsare III-V materials.

In embodiments of the invention, the III-V material is gallium nitride(GaN). With this approach, a thin film layer 218 having general formulaSi_(x)N_(y) is formed under the second semiconductor layer 216 due tonucleation process during the epitaxial growth of the secondsemiconductor layer 216 on the semiconductor substrate 10. In otherwords, the film layer 218 separates the second semiconductor layer 216(i.e., GaN layer) from the semiconductor substrate 10 (i.e., Si (100)layer).

The III-V material(s) deposited in the second substrate region 112 canbe deposited as a single layer or as multiple layers, each layercontaining a III-V material. Thus, the second semiconductor layer 216can be made up of a single layer of a III-V material or alternatively,multiple layers (in a stacked configuration) each layer containing aIII-V material.

In FIG. 4, a third semiconductor layer 214 is formed over the secondsemiconductor layer 216 in the second substrate region 112. The thirdsemiconductor layer 214 is formed by epitaxial growth, and composed ofsilicon with orientation (111) (Si (111)). In other words, according toembodiments of the invention, as further described below, the n-VFETregion 611 (shown in FIG. 6) is formed in the first substrate region111, including the first semiconductor layer 12 composed of Si (100),and the p-VFET region 612 (shown in FIG. 6) is formed in the secondsubstrate region 112, including the second semiconductor layer 216 andthe third semiconductor layer 214 composed of Si (111).

In FIG. 5, a hard mask 14A is formed by any conventional method (forexample, methods described above) over the upper surface of thesemiconductor layer 114 in the second substrate region 112. The hardmask 14A is flush with the hard mask 14. In embodiments of theinvention, the hard mask 14A includes SiN.

In FIG. 6, a first channel 620 is formed over the first substrate region111 (i.e. the n-VFET region 611), and a second channel 640 is formedfrom over the second substrate region (i.e. the p-VFET region 612).According to the embodiments of the invention, the layers 12, 214, 216and 218 have been etched using a selective, directional etch (e.g., RIE)to form the first channel 620 and the second channel 640 in the n-VFETregion 611 and the p-VFET region 612, respectively. Further, the firstchannel 620 and second channel 640 can be formed by a sidewall imagetransfer (SIT) process, self-aligned double patterning (SADP) process,or self-aligned quadruple patterning (SAQP) process, to provide a tightpitch between the first channel 620 and the second channel 640.According to embodiments of the invention (as shown in FIG. 6), theuppermost surface of the hard mask 14A is coplanar with the uppermostsurface of the hard mask 14. In other words, the first channel 620 andsecond channel 640 are of equal height.

As further shown in FIG. 6, interlayer dielectric (ILD) material 601 isdeposited in empty regions that surround the first channel 620 and thesecond channel 640. The ILD material 601 is substantially coplanar withthe upper surfaces of the hard masks 14 and 14A following a chemicalmechanical polishing (CMP) process.

In FIG. 7, a first top spacer 804 is formed over the first channel 620and a second top spacer 806 is formed over the second channel 640.

As shown in FIG. 8, the first top spacer 804 and the second top spacer806 can be formed by direct deposition and RIE or another suitableprocesses, and can include SiN or other nitride. Prior to the directdeposition described above, the ILD material 601 has been recessed.

FIG. 9 illustrates a bottom source/drain layer 910 being formed over theILD material 601. The bottom source/drain layer 910 will serve as thebasis for forming the bottom source/drain region of the applicable VFET.According to embodiments of the invention, doping of the bottomsource/drain layer 910 can be performed in-situ or ex-situ. By in-situit is meant that dopants are introduced during epitaxial growth of layer910. In-situ doping involves introducing the dopants (e.g., via ionimplantation) following epitaxial growth of the layer 910. Thecomposition of layer 910 and the dopants vary depending on the type ofVFET being formed. By way of example only, for a p-channel a suitablecomposition for layer 910 is boron (B) doped SiGe, whereas for ann-channel a suitable composition for layer 910 is phosphorous (P) dopedsilicon carbide (SiC). The bottom source/drain layer 910 can be formedby epitaxial growth, as well as an epitaxial pre-cleaning process, whichis performed prior to growing the bottom source/drain layer 910, whichinvolves etching the uppermost surface of the ILD material 601.

As illustrated in FIG. 10, bottom spacers 915 are formed on the bottomsource/drain layer 910 on opposite sides of the first channel 620 andthe second channel 640. The bottom spacers 915 can be formed bydepositing a suitable spacer material over the bottom source/drain layer910, and then patterning the spacer material into the individual bottomspacers 915. Suitable spacer materials include, but are not limited to,oxides such as silicon oxide (SiO₂), nitrides such as silicon nitride(SiN), and/or low-K materials such as carbon-doped oxide materialscontaining silicon (Si), carbon (C), oxygen (O), and hydrogen (H)(SiCOH) or siliconborocarbonitride (SiBCN). The term “low-κ” as usedherein refers to a material having a relative dielectric constant κwhich is lower than that of silicon nitride.

During this step, as shown in FIG. 11, the first top spacer 804 and thesecond top spacer 806 can also be removed from the sidewalls of thefirst channel 620 and the second channel 640 by conventional methods,such as isotropic plasma etching.

In FIG. 12, a gate dielectric (e.g., high-k dielectric) layer 1201 isconformally deposited over upper surfaces of the bottom spacers 915,sidewalls of the first channel 620 and the second channel 640, andcorresponding sidewalls and upper surfaces of the hard masks 14 and 14A.Thus, the high-k dielectric layer 1201 includes a lower portions 1201Arunning along the bottom spacers 915, a sidewall portions 1201B runningalong the respective sidewalls of the first channel 620 and the secondchannel 640, and the hard masks 14 and 14A, and an upper portions 1201Crunning along the upper surfaces of the hard masks 14 and 14A. Aconformal setting metal layer 1203 is deposited onto the gate dielectriclayer 1201 (e.g., high-k dielectric), for example, by CVD or ALD. Theparticular work function metal used can vary depending on whether ann-type or p-type transistor is desired. For instance, suitable n-typework function metals include, but are not limited to, titanium nitride(TiN), tantalum nitride (TaN), and aluminum (Al)-containing alloys suchas titanium aluminide (TiAl), titanium aluminum nitride (TiAlN),titanium aluminum carbide (TiAlC), tantalum aluminide (TaAl), tantalumaluminum nitride (TaAlN), and tantalum aluminum carbide (TaAlC).Suitable p-type work function metals include, but are not limited to,TiN, TaN, and tungsten (W). Suitable low resistance gate metals include,but are not limited to tungsten (W) and/or aluminum (Al). As shown inFIG. 13, the metal layer 1203 seals the gate dielectric layer 1201.

As further shown in FIG. 12, an interlayer dielectric (ILD) material610A is deposited in empty regions along the gate dielectric (e.g.,high-k dielectric) layer 1201 and conformal setting metal layer 1203.The ILD material 610A is substantially coplanar with the conformalsetting metal layer 1203 that covers the upper portions 1201C followinga chemical mechanical polishing (CMP) process.

In FIG. 13, a shallow trench isolation (STI) patterning is conducted toseparate the continuous gate layer 1301 and the gate dielectric layer1201 to form a gate layer 1301A and a gate layer 1301B, corresponding tothe first channel 620 and the second channel 640, respectively. The ILDmaterial 610A is recessed and polished back to expose the upper portions1201C of the gate dielectric (e.g., high-k dielectric) layer 1201surrounded by the top spacer material 1203.

In FIG. 14, a top spacer metal 1401 is directionally deposited over theuppermost portion of the ILD material 610A. Suitable spacer materialsinclude, but are not limited to, oxides such as SiO₂, nitrides such asSiN, and/or low-κ materials such as SiCOH or SiBCN. As shown in FIG. 14,the top spacer material 1401 seals the gate dielectric (e.g., high-kdielectric) layers 1201A and 1201B.

The structure is then surrounded with a filler dielectric 610C. Thefiller dielectric 610C is coplanar with the upper portions 1201C. Thefiller dielectric 610C is then polished back (i.e., recessed) to exposethe top spacer material 1401 around the first channel 620 and the secondchannel 640, as shown in FIG. 14. Suitable dielectrics include, but arenot limited to, SiO₂ and low-κ inter-layer dielectrics, such as SiCOH orSiBCN. Polishing back filler dielectric 610C can be achieved using aprocess such as chemical mechanical polishing or CMP.

In FIG. 15, the hard masks 14 and 14A have been removed by conventionalmethods. Top source/drain regions 1505A and 1505B are then formed bycoplanar epitaxy over the first channel 620 and the second channel 640,respectively. Similar to the doping of the bottom source/drain layer910, the doping of the top source/drain regions 1505A and 1505B can beperformed in-situ or ex-situ, and the composition of the topsource/drain regions 1505A and 1505B and the dopants can vary dependingon the type of VFET being formed.

As also shown in FIG. 15, a plurality of epitaxial contacts 1510A,1510B, 1511A and 1511B are grown substantially simultaneously by n-typein-situ doped epitaxial growth processes (e.g., in-situ phosphorus dopedsilicon epitaxy). The epitaxial contacts 1510A and 1510B are disposedover the first channel 620 and the second channel 640, respectively. Inaccordance with embodiments of the invention, first one of the epitaxialcontacts (namely, 1510A) is provided as n-VFET top source and draincontact, while second one of the epitaxial contacts (namely, 1510B) isprovided as p-VFET top source and drain contact.

With reference to FIG. 15, formation of the integrated device accordingto the invention is completed.

It is to be understood that the process illustrated in FIGS. 1-15 can berevised such that the third semiconductor layer 214 (composed of Si(111)) is formed directly over the semiconductor substrate 10 in thesecond substrate region 112 by any conventional methods.

The methods described herein can be used in the fabrication of IC chips.The resulting integrated circuit chips can be distributed by thefabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

Various embodiments of the present invention are described herein withreference to the related drawings. Alternative embodiments can bedevised without departing from the scope of this invention. Althoughvarious connections and positional relationships (e.g., over, below,adjacent, etc.) are set forth between elements in the followingdescription and in the drawings, persons skilled in the art willrecognize that many of the positional relationships described herein areorientation-independent when the described functionality is maintainedeven though the orientation is changed. These connections and/orpositional relationships, unless specified otherwise, can be direct orindirect, and the present invention is not intended to be limiting inthis respect. Similarly, the term “coupled” and variations thereofdescribes having a communications path between two elements and does notimply a direct connection between the elements with no interveningelements/connections between them. All of these variations areconsidered a part of the specification. Accordingly, a coupling ofentities can refer to either a direct or an indirect coupling, and apositional relationship between entities can be a direct or indirectpositional relationship. As an example of an indirect positionalrelationship, references in the present description to forming layer “A”over layer “B” include situations in which one or more intermediatelayers (e.g., layer “C”) is between layer “A” and layer “B” as long asthe relevant characteristics and functionalities of layer “A” and layer“B” are not substantially changed by the intermediate layer(s).

The following definitions and abbreviations are to be used for theinterpretation of the claims and the specification. As used herein, theterms “comprises,” “comprising,” “includes,” “including,” “has,”“having,” “contains” or “containing,” or any other variation thereof,are intended to cover a non-exclusive inclusion. For example, acomposition, a mixture, process, method, article, or apparatus thatcomprises a list of elements is not necessarily limited to only thoseelements but can include other elements not expressly listed or inherentto such composition, mixture, process, method, article, or apparatus.

Additionally, the term “exemplary” is used herein to mean “serving as anexample, instance or illustration.” Any embodiment or design describedherein as “exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments or designs. The terms “at least one”and “one or more” are understood to include any integer number greaterthan or equal to one, i.e. one, two, three, four, etc. The terms “aplurality” are understood to include any integer number greater than orequal to two, i.e. two, three, four, five, etc. The term “connection”can include an indirect “connection” and a direct “connection.”

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” etc., indicate that the embodiment describedcan include a particular feature, structure, or characteristic, butevery embodiment may or may not include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

For purposes of the description hereinafter, the terms “upper,” “lower,”“right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” andderivatives thereof shall relate to the described structures andmethods, as oriented in the drawing figures. The terms “overlying,”“atop,” “on top,” “positioned on” or “positioned atop” mean that a firstelement, such as a first structure, is present on a second element, suchas a second structure, wherein intervening elements such as an interfacestructure can be present between the first element and the secondelement. The term “direct contact” means that a first element, such as afirst structure, and a second element, such as a second structure, areconnected without any intermediary conducting, insulating orsemiconductor layers at the interface of the two elements.

Spatially relative terms, e.g., “beneath,” “below,” “lower,” “above,”“upper,” and the like, can be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the term “below” can encompass both an orientation ofabove and below. The device can be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

The terms “about,” “substantially,” “approximately,” and variationsthereof, are intended to include the degree of error associated withmeasurement of the particular quantity based upon the equipmentavailable at the time of filing the application. For example, “about”can include a range of ±8% or 5%, or 2% of a given value.

The phrase “selective to,” such as, for example, “a first elementselective to a second element,” means that the first element can beetched and the second element can act as an etch stop.

The term “conformal” (e.g., a conformal layer) means that the thicknessof the layer is substantially the same on all surfaces, or that thethickness variation is less than 15% of the nominal thickness of thelayer.

The terms “epitaxial growth and/or deposition” and “epitaxially formedand/or grown” mean the growth of a semiconductor material (crystallinematerial) on a deposition surface of another semiconductor material(crystalline material), in which the semiconductor material being grown(crystalline overlayer) has substantially the same crystallinecharacteristics as the semiconductor material of the deposition surface(seed material). In an epitaxial deposition process, the chemicalreactants provided by the source gases can be controlled and the systemparameters can be set so that the depositing atoms arrive at thedeposition surface of the semiconductor substrate with sufficient energyto move about on the surface such that the depositing atoms orientthemselves to the crystal arrangement of the atoms of the depositionsurface. An epitaxially grown semiconductor material can havesubstantially the same crystalline characteristics as the depositionsurface on which the epitaxially grown material is formed. For example,an epitaxially grown semiconductor material deposited on a (100)orientated crystalline surface can take on a (100) orientation. In someembodiments of the invention, epitaxial growth and/or depositionprocesses can be selective to forming on semiconductor surface, andcannot deposit material on exposed surfaces, such as silicon dioxide orsilicon nitride surfaces.

As previously noted herein, for the sake of brevity, conventionaltechniques related to semiconductor device and integrated circuit (IC)fabrication may or may not be described in detail herein. By way ofbackground, however, a more general description of the semiconductordevice fabrication processes that can be utilized in implementing one ormore embodiments of the present invention will now be provided. Althoughspecific fabrication operations used in implementing one or moreembodiments of the present invention can be individually known, thedescribed combination of operations and/or resulting structures of thepresent invention are unique. Thus, the unique combination of theoperations described in connection with the fabrication of asemiconductor device according to the present invention utilize avariety of individually known physical and chemical processes performedon a semiconductor (e.g., silicon) substrate, some of which aredescribed in the immediately following paragraphs.

In general, the various processes used to form a micro-chip that will bepackaged into an IC fall into four general categories, namely, filmdeposition, removal/etching, semiconductor doping andpatterning/lithography. Deposition is any process that grows, coats, orotherwise transfers a material onto the wafer. Available technologiesinclude physical vapor deposition (PVD), chemical vapor deposition(CVD), electrochemical deposition (ECD), molecular beam epitaxy (MBE)and more recently, atomic layer deposition (ALD) among others.Removal/etching is any process that removes material from the wafer.Examples include etch processes (either wet or dry), chemical-mechanicalplanarization (CMP), and the like. Reactive ion etching (RIE), forexample, is a type of dry etching that uses chemically reactive plasmato remove a material, such as a masked pattern of semiconductormaterial, by exposing the material to a bombardment of ions thatdislodge portions of the material from the exposed surface. The plasmais typically generated under low pressure (vacuum) by an electromagneticfield. Semiconductor doping is the modification of electrical propertiesby doping, for example, transistor sources and drains, generally bydiffusion and/or by ion implantation. These doping processes arefollowed by furnace annealing or by rapid thermal annealing (RTA).Annealing serves to activate the implanted dopants. Films of bothconductors (e.g., poly-silicon, aluminum, copper, etc.) and insulators(e.g., various forms of silicon dioxide, silicon nitride, etc.) are usedto connect and isolate transistors and their components. Selectivedoping of various regions of the semiconductor substrate allows theconductivity of the substrate to be changed with the application ofvoltage. By creating structures of these various components, millions oftransistors can be built and wired together to form the complexcircuitry of a modern microelectronic device. Semiconductor lithographyis the formation of three-dimensional relief images or patterns on thesemiconductor substrate for subsequent transfer of the pattern to thesubstrate. In semiconductor lithography, the patterns are formed by alight sensitive polymer called a photo-resist. To build the complexstructures that make up a transistor and the many wires that connect themillions of transistors of a circuit, lithography and etch patterntransfer steps are repeated multiple times. Each pattern being printedon the wafer is aligned to the previously formed patterns and slowly theconductors, insulators and selectively doped regions are built up toform the final device.

The flowchart and block diagrams in the Figures illustrate possibleimplementations of fabrication and/or operation methods according tovarious embodiments of the present invention. Variousfunctions/operations of the method are represented in the flow diagramby blocks. In some alternative implementations, the functions noted inthe blocks can occur out of the order noted in the Figures. For example,two blocks shown in succession can, in fact, be executed substantiallyconcurrently, or the blocks can sometimes be executed in the reverseorder, depending upon the functionality involved.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments described. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdescribed herein.

What is claimed is:
 1. An integrated semiconductor device comprising: asubstrate comprising a first substrate region and a second substrateregion; a first vertical transistor disposed on the substrate in thefirst substrate region, wherein the first vertical transistor is n-typefield-effect vertical transistor (n-VFET) with a first channelcrystalline orientation; a second vertical transistor disposed on thesubstrate in the second substrate region, wherein the second verticaltransistor is p-type field-effect vertical transistor (p-VFET) with asecond channel crystalline orientation, wherein the first channelcrystalline orientation is different from the second channelorientation; a common bottom source and drain region for the firstvertical transistor and the second vertical transistor; a common bottomspacer region for the first vertical transistor and the second verticaltransistor; and a common top spacer region for the first verticaltransistor and the second vertical transistor.
 2. The integratedsemiconductor device according to claim 1, wherein the first channelcrystalline orientation is (100) and the second channel crystallineorientation is (111).
 3. The integrated semiconductor device accordingto claim 1, wherein a fin of the first vertical transistor comprisessilicon (Si) with (100) crystal orientation (Si (100)) and a fin of thesecond vertical transistor comprises silicon (Si) with (111) crystalorientation (Si (111)).
 4. The integrated semiconductor device accordingto claim 1, wherein a fin of the second vertical transistor comprises aIII-V material, selected from the group consisting of aluminumantimonide, aluminum arsenide, aluminum gallium arsenide, aluminumgallium indium phosphide, aluminum gallium nitride, aluminum galliumphosphide, aluminum indium arsenide, aluminum nitride, aluminumphosphide, boron arsenide, boron nitride, boron phosphide, galliumantimonide, gallium arsenide, gallium arsenide phosphide, gallium indiumarsenide antimonide phosphide, gallium nitride, gallium phosphide,indium antimonide, indium arsenide, indium arsenide antimonidephosphide, indium gallium arsenide, indium gallium nitride, indiumgallium phosphide, indium nitride, indium phosphide and/or combinationsthereof.
 5. The integrated semiconductor device according to claim 4,wherein the III-V material is gallium nitride (GaN).
 6. The integratedsemiconductor device according to claim 5, wherein the fin of the secondvertical transistor further comprises a film layer composed of acompound of formula Si_(x)N_(y).
 7. The integrated semiconductor deviceaccording to claim 1, wherein uppermost portions of a fin of the firstvertical transistor and a fin of the second vertical transistor arecoplanar.
 8. The integrated semiconductor device according to claim 1further comprising an interlayer dielectric (ILD) disposed around andover the first vertical transistor and the second vertical transistor.9. An integrated semiconductor device comprising: a first fin channel ona substrate, the first fin channel comprising silicon having a (100)crystal orientation; a second fin channel over the substrate, the secondfin channel comprising silicon having a (111) crystal orientation; abuffer layer positioned between the second fin channel and thesubstrate; an isolation layer positioned between the buffer layer andthe substrate; wherein a topmost surface of the first fin channel iscoplanar to a topmost surface of the second fin channel.
 10. Theintegrated semiconductor device according to claim 9, wherein the bufferlayer comprises a III-V semiconductor material.
 11. The integratedsemiconductor device according to claim 10, wherein the buffer layercomprises gallium nitride (GaN).
 12. The integrated semiconductor deviceaccording to claim 9, wherein the isolation layer comprises a compoundhaving a formula Si_(x)N_(y).
 13. The integrated semiconductor deviceaccording to claim 9 further comprising a common top spacer between thefirst fin channel and the second fin channel.
 14. The integratedsemiconductor device according to claim 13 further comprising a firsttop source or drain region on the topmost surface of the first finchannel and a second top source or drain region on the topmost surfaceof the second fin channel.
 15. The integrated semiconductor deviceaccording to claim 14, wherein the first top source or drain region ispositioned on a surface of the common top spacer and the second topsource or drain region is positioned on the surface of the common topspacer.
 16. The integrated semiconductor device according to claim 15,wherein a bottommost surface of the first top source or drain region iscoplanar to a bottommost surface of the second top source or drainregion.
 17. The integrated semiconductor device according to claim 9further comprising a common bottom source or drain region formed overthe substrate.
 18. The integrated semiconductor device according toclaim 17 further comprising a common bottom spacer positioned on thecommon bottom source or drain region.
 19. The integrated semiconductordevice according to claim 18, wherein a first sidewall of the commonbottom spacer is in direct contact with a sidewall of the first finchannel and a second sidewall of the common bottom spacer is in directcontact with a sidewall of the second fin channel.
 20. The integratedsemiconductor device according to claim 9, wherein a bottommost surfaceof the first fin channel is coplanar to a bottommost surface of theisolation layer.